Malorie Blackman suggests literature could be a safer space than pornography for children to learn about sex. Why is that controversial, asks Hannah Betts. Photograph: Christian Sinibaldi for the Guardian

In a sentence so repugnantly lenient that the attorney general was immediately compelled to review it, this week television veteran Stuart Hall was given 15 months for 14 assaults on girls as young as nine. This qualifies as four weeks per attack, give or take; or rather, a fortnight, given that he is set to serve just seven and a half months.

Judge Anthony Russell argued that part of his justification for this outrage was 83-year-old Hall's octogenarian status: "Your age is an appropriate factor to take into account because, for a man of your age, a custodial sentence would be particularly difficult." Rather less difficult than being sexually assaulted at the age of nine, one might have thought.

In a statement that smacked of the most lamentable irony, the Crown Prosecution Service responded: "We hope Stuart Hall's prosecution gives abuse victims confidence to come forward; they will be believed and they will be listened to" – and, clearly, their experiences will then be disregarded. Hall's sentence is as condescending to the old as it is insulting to the young. Russell appeared to dismiss Hall's crimes as a particularly avuncular, Lite Entertainment form of paedophilia. An upskirt, perhaps?

Meanwhile, evidence was heard in the case against Jeremy Forrest, the teacher found guilty of abducting a schoolgirl and taking her to France. The pair began their affair when she was 14, having sex a year later, at the very least qualifying his actions as rape. The prosecution argued that Forrest was no star-crossed Romeo, but a "paedophile" who "groomed" the teenager in question. His defence lawyer Humbert Humbert-ly blamed the child for his behaviour, claiming that she was "very desperate, had suicidal thoughts and was assertive" (the former not surprising in the circumstances). And, if that failed to wash, his sister was on call to blame the wife. Happily, the jury remained unconvinced.

Curious, then, in such a week, that outrage should be directed at children's laureate Malorie Blackman for calling for more depictions of sex in fiction. In a statement echoed by fellow authors Melvin Burgess and Philip Pullman, Blackman argued that literature would provide a safer space for exploration than "brutalising" images in online pornography. The idea did not sound that controversial in an age in which a quarter of internet inquiries and third of downloads are explicit. Still, her observation provoked the obligatory Mexican wave of horror.

Children and sex: it is a combination that throws us into cultural panic. For all the right, Hall- and Forrest-type reasons, we fear the sexual contamination of our young to the point of hysteria. However, there is the world of difference between seeking to avoid exploitation of children by malign and calculating adults, and an acknowledgement that sex makes up an aspect of their being about which they deserve to be educated.

Perhaps it was Freud who at once liberated us to consider, yet rendered us so hotly neurotic, about all this. As my psychoanalysis-scorning, former-psychiatrist father is wont to opine, Freud's decision that the abuse narratives of youngsters he encountered were imaginary "held treatment back 50 years"; a view advocated by social worker and feminist theorist Florence Rush in her Freudian cover-up theory. The anxiety over this legacy has made society rightly vigilant about the handling of abuse complaints.

Yet it would also appear to have left us with a collective horror not merely of adult-child molestation, but of the notion that children's sexual feelings might exist at all.

Unpalatable as it is to some, sexual instinct is not something that begins conveniently when the law grants it at 16. Children are never not sexual, even before birth. Males may experience erections in the womb, at birth and while babies; both genders stimulate themselves while babies and toddlers, both are orgasmic (even if ejaculation is delayed until puberty). And they harbour a natural interest in such matters as they do all other fundamental activities.

Recently, when I explained to my eight-year-old niece that I could not FaceTime her as I was flirting, she left me a chirpy video message instructing me to: "Go and do sex on a boy." The mechanics might sound a tad lap-dancerish, but I approve of the sentiment. It represents a mutual frankness that means that she can confide in me about her own erotic pursuits – both now and in the future, when the stakes may be rather higher.

Young people deprived of such openness will discover a way to seek information out: if not via Blackman and Burgess, then somewhere else. Every generation finds its educative pornutopia. For our grandparents, it constituted an incentive to translate Ovid; for our parents, Lady Chatterley concealed in a brown paper bag; for my own generation, the god-awful Lace, with its infamous goldfish scene, and whose adventuresses promised to remain united "through sick and sin".

Blackman is right: if the young cannot find such material in print, they will seek it – potentially more violently and disturbingly – online. At which point, may I steer all teenagers (and some over-optimistic male divorcees) toward the "Know It" section of makelovenotporn.com?

This genial site marks feminist entrepreneur and TED lecturer Cindy Gallop's differentiation of porn sex from real sex as a cultural caveat by way of sex ed.

Accordingly, it explains that not all women want men to ejaculate on their faces all the time, that sex does not have to be awash with saliva, and that skin-on-skin (as oppose to angular, acrobatic, genital-only) contact can be rather fun.

If we deny teens and younger children knowledge about intercourse, then we leave them in a peculiarly 21st-century situation in which sex is fictionally omnipresent yet factivelyabsent. Youths of yore, who may have heard or seen their parents during the act, viewed sex in a wider, less physically isolated context. Today's young see sex's manifestations all about them – from porn itself to sexualised music videos and prepubescent clothing. Fucking – a term that, believe me, they know – is everywhere.

The more dangerous and bitter irony is that – when we treat sex as aberrantly out of bounds, glossed over with a mystifying menagerie of storks, birds and bees – it serves only to leave children prey to the counter-fictions of a Forrest or Hall.

One does not have to be a mortifyingly "trendy adult" who rubs nipperish noses in such matters. However, honesty about sex is not only what children deserve, but what will preserve them from assaults on ignorance masquerading as innocence. It is time for adults to grow up and arm our young with honesty.